Surface characterisation and electrochemical stability of anodised new alloy in simulated physiological electrolytes

Abstract

In this paper, we applied the potentiostatic anodisation method on the new Ti-20Nb-10Zr-5Ta alloy surface with the aim to increase its stability and bioactivity. The morphology (SEM) and composition (Raman, FT-IR) of the obtained anodisation nanolayer are studied. Also, electrochemical stability (by cyclic potentiodynamic polarisation and EIS), corrosion resistance (by linear polarisation), long-term behaviour (by monitoring of the open circuit potentials and corresponding open circuit potential gradients) and the characterisation of the layers deposited on the alloy surface after 1000 h in acid, neutral and alkaline Ringer and neutral Ringer-Brown solutions are presented. By potentiostatic anodisation, on the alloy surface was electrodeposited a continuous nanolayer containing TiO 2 rutile type oxide. The anodised layer possesses better protective properties and at the same time better porosity, therefore a higher stability and bioactivity in comparison with the native passive film. After 1000 h in the testing solutions promoted the deposition of the brushite, phosphatotitanate and hydroxyapatite, precursors, respectively component of the human bone, namely this layer is bioactive.

Long-term corrosion behavior and biocompatibility testing of titanium-based alloy covered with nano-crystalline hydroxyapatite

“…Various methods were used to coat the implant alloy surfaces with the aim to combine the metal mechanical properties with the bone‐bonding ability of the bioactive coatings . The most important techniques are: plasma spraying , magnetron‐sputtering , micro arc oxidation , sol–gel , electrodeposition by potentiostatic and galvanostatic polarization, heat and alkali treatments , doped , ion implantation , chemical deposition in solutions containing calcium and phosphorus ions , electrophoretic deposition , etc. Some of the above mentioned methods presented drawbacks related to the coating delamination, the impossibility to be applied on complex shapes, high cost, power consumption, pollution due to the use of aggressive solutions, etc.…”